This invention relates to a tube coupling assembly or unit of the general type disclosed in U.S. Pat. No. 3,425,717 which issued to the assignee of the present invention. In this coupling unit a bail-type actuating member 32 is pivoted on screws 45 for rotating eccentric cams 33 which move an external cap 25 and an internal socket member 18 axially for releasably compressing an annular resilient seal 19 against a tube and for moving a spring collet 21 between a release position (FIG. 1) and a tube gripping position shown in (FIG. 2). Another form of tube coupling device or unit is disclosed in U.S. Pat. No. 4,884,830. In this unit, an outer tubular sleeve 28 moves axially on a tubular coupling body for camming a plurality of balls 24 inwardly to move or cam an internal tubular actuating member from a tube gripping and sealing position, (FIGS. 2 & 3) to a released position (FIG. 1).
It has been found desirable for any such tube coupling device or unit to provide the safety feature of anti-blowoff so that the higher the pressure within the coupling unit, the higher the gripping and sealing force on the tube. It is also desirable for the unit to be constructed for easy operation and convenient replacement of the resilient sealing rings. The coupling unit should also be constructed with a minimum of components which may be easily assembled in order to minimize the construction costs for the unit.